Heat exchangers, such as are typically employed in air conditioning systems for example for automobiles, generally comprise a large number of heat exchange tubes which carry coolant fluid, connected to a manifold. The manifold is internally divided into a plurality of compartments including an inlet compartment to which a fluid inlet line is connected, an outlet compartment to which a fluid outlet line is connected, and a further intermediate compartment or compartments, so that a tortuous multi-pass path for coolant fluid is defined by the manifold and heat exchange tubes. Heat exchange occurs between the coolant fluid passing through the heat exchange tubes, and surrounding air.
Such internally divided manifolds are difficult to form and to assemble. Conventionally, the manifold comprises two-half shells in the form of a header part which is provided with apertures for the heat exchange tubes, and a tank part. These parts include internal walls cast, welded or brazed therein, and are connected together by, for example, brazing to form the complete manifold. Such an arrangement requires the parts to be formed with very high precision. If the walls are not very accurately positioned they may obscure or partially obscure openings in the manifold wall for the heat exchange tubes, restricting fluid flow or causing leaking reduces the effectiveness of heat transfer and functionality.
It is also known to provide a unitary tubular manifold, into which internal wall members are introduced and brazed in position. For example, it has been proposed to form additional slots in the manifold wall, through which internal baffles are introduced and then brazed in position. A drawback of this arrangement is that manufacture of the tubular wall is complicated by the need to provide precision slots. These slots also give rise to possible additional external leakage points.
Other arrangements require the precision forming of seats or locating surfaces on the inner surfaces of the manifold for the internal partitions or baffles.
It has also been proposed by the applicants to provide a unitary tubular manifold, and to provide the internal walls as well as end walls in the form of baffles which are held on a guide rail. On assembly, the baffles are first located on the guide rail which is subsequently introduced into the tubular manifold from one end thereof. This arrangement avoids the need for slots for the introduction of internal walls, or for the provision of seats or sealing surfaces on the internal surface of the tubular manifold housing. It has, however, been found to be difficult to introduce the assembly of guide rail and baffles if there are any casting irregularities in the form of flash or burr on the inside of the tubular manifold.